Bigger is better, but 3.8 meters per second is what... 8.5 MPH ?? VERY low and un-practical wind speed. Barely even cut-in wind speed for most turbines, large or small. I'd say this test is flawed for that very reason.

And did the say how high the turbines were ? And their larger reference turbine ? Is that reference turbine the tower in the background that is WAY up there ? (probably not, but I don't know)

According the the [URL="http://www.ecologik.ca/pdf/Wind Page/Lagerwey File/LW18-80description.pdf"]PDF of the specs. for the large wind turbine[/URL], the standard tower is 30 meters with an option to 40 meters.

Interestingly, the system is a AC/DC/AC inverter system (not a synchronous 3 phase motor to the AC power line frequency).

So--given that the total installed cost of the one large wind turbine was about the same as the 12 smaller wind turbines in total (30 meters high, in a windy region of the Netherlands) and the one large system generated about 20x the amount of power...

The test was funded by:
- Stichting Zeeuwind (wind energy)
- Greenlab (small scale renewable energy, focused on wind energy and tidal energy)
- DELTA NV (gas, electricity, solar, internet, tv, water)
- Provincie Zeeland (government)
- Gemeente Sluis (local government).
This test was not designed to give the small wind industry a bad name, on the contrary. These small windmills are designed and promoted for use in a built-up environment, where the average wind speeds are almost always lower than 8.5 mph. They were friendly enough to install them in an unobstructed area, and they decided not to include the results from November 2007 to March 2008, when many windmills showed problems.
See the windmap of Holland and the article we published before:http://www.nkpw.nl/images/stories/KNMI%20Windsnelheid%201971%202000.jpghttp://www.lowtechmagazine.com/2008/09/urban-windmills.html

From the 2008 article (2nd link above) there is a lot more details about the installation/testing.

Basically, went to a very windy province in Netherlands, in clear/open fields, and installed wind turbines advertised for urban areas (small rotors, short towers, lots of wind obstructions)--so this was "ideal" testing.

From this PDF file, the average wind at the test site (in meters per second, by month and 1 year average--slightly winder than average--I am guessing this is at 10 meter height since they were documenting smaller wind turbines on 10-13 meter tall towers--I think):

Interestingly--I found out you can use Google Language to translate PDF files as well as websites (graphics will not be pretty--but at least you can read the text).

In the end, the 2008 article says:

At lower average wind speeds, even very small changes can make a huge difference. According to the Carbon Trust the cut-in speed of a small wind turbine (the moment it starts producing energy) is between 3 and 4 metres per second. This is close to the average wind speed on land in rather windy countries like Belgium and the Netherlands.

A test by the Carbon Trust (see graphics below) showed that a windmill receiving an average wind speed of 4.5 metres per second produced 7 times more energy than a windmill receiving an average wind speed of 3 metres per second – because the latter is not operating most of the time since it does not reach its cut-in speed. While large wind turbines have an average capacity factor of 28 to 35 percent, small windmills only achieve 15 to 20 percent of their capacity in rural areas and only 10 percent in urban areas.

Regarding tower height--Scaling a few of the pictures against rotor diameter seems to show the turbines are around 12-13 meters high (~40 feet?)... And the articles talk about the rarity of 10 meter wind maps (vs 75 meter wind maps that which are widely available)--so I would guess the 12 test towers are at least 10 meters tall.

This "test" was certainly a joke, but it does make an important point. Tiny vertical axis machines don't produce enough power to bother with, and short towers don't work. I would never recommend anything less than 60 feet for a tower, and 120 is certainly much better. It is funny to me that the Skystream did the best in these tests, as it is gaining a reputation in the USA of not performing reliably or up to predictions. There are some good machines out there, but they generally have at least a 10 foot diameter rotor, and are mounted on tall towers by reputable installers, in areas with at least 10mph average windspeed.

Aside from the basic (un) reliability of small scale wind machines,,, IMHO the biggest mistake people make with regards to small scale wind is over estimating how hard the wind is REALLY blowing,,, on average. A 12 mph average is a REALLY windy place. If you are not constantly irritated about the wind "blowing all the time" disrupting activity, you probably don't have enough wind to make it even worth a cheap try.

I agree if you do not have a windy site it is going to be a long payback

If you don't have 10mph or more (get it professionally measured if possible) it is like putting up a 2000 watt solar panel array in the middle of the rain forest on the olympic pennisula under a heavy spruce canopy

I stand by my point; I didn't say the test was "fair" or "valid" or any other description except "legit" - legitimate.

But actually, it was valid, if for no other reason than that it demonstrated conclusively that an 8.5mph average wind speed is too low for most small wind turbines to put out a significant amount of power. That is a "valid" conclusion resulting from this test (an expensive way to reach that conclusion yes, but experiments can sometimes be expensive for little or no return).

Nevertheless, it was legitimate; They set the units up next to each other, in what they consider to be a windy area of their country, they monitored, they ran it for a year.

No hype, no "optimum conditions" BS, just a simple little "real world" experiment.

Now, as to my reasoning for this thread being a sticky - that it would be a good thread to answer some newbie questions - again, I stand by that. With the posts that this thread has already generated, it has become very informative.

For example:

* 8.5mph average wind speed is too low for most small wind turbines (but not all).

* Any average wind speed under 10 mph is a very poor wind power site.

* Most people overestimate the average wind in their area.

* The people who setup this experiment overestimated the average wind for the test site (they expected 6 meters per second average).

* 10 meters height is too low for most turbines in most places.

* A windmill receiving an average wind speed of 4.5 meters per second produces 7 times more energy than a windmill receiving an average wind speed of 3 meters per second.

* Small windmills only achieve 15 to 20 percent of their capacity in rural areas and only 10 percent in urban areas.

* The energy in wind goes up as the cube of the wind speed.

* The power output of a turbine is directly proportional to the swept area.

* When you double the radius of a turbine, you increase the swept area by a factor of four.

* 3 out of 12 (25%) of the small turbines in the one year test broke down.

It speaks clearly as to why small scale wind proves not to be very practicable for most people. The 10 meter rule is hard enough for most people. The idea of raising anything 10 meters off the ground sounds easy,,, until you have to do it. Add to that the idea of guying and bracing that load against huge potential storm loading,,, and it is no wonder that so many of them fail.

I would love to put up a nice, cheap, small (200-400 watt) rig to augment our charging,,, but I don't think one exist. On the other hand I could mount on on a pole on the ice and hmmm!

As I have always wished for a simple small wind genny,,, and this thread always relights that fire,, I went looking and our Local Canadian tire has the Air X 400 on sale for ~$550 usd net,,, not too bad for a toy if one wanted to play.

I guess for the same $550 I could buy two more Sun 90's for another 180 watts,,something I would need a consistent ~25mph to get close to with the Air X. Not only that,, but in 24/7 service I would bet that the PV panels will still be putting out rated current 5 years from now,,, not likely the Air X.

180 watts of PV/50%=90 watts net X 4 hours/day average=360 whd,, averaged over 30 days of 1/2 sun you would get 5.4kwh. over a year=~65kwh/yr.

Air X 400 putting out 100 watts 4 hours/day/50% =200 wh/day X (?) 50% windy days X 365 might be 36kwh. That's figuring 20 mph for 4 hours 1/2 the days of the year,,, not likely where I am. I get lots of wind in spurts,,but calm nights are common winter and summer, days with 5-10 mph quite common,, days with 25-20 1 day in 10 in the summer,, 1 in 5 in the winter.

you're right tony and to add to that the air x will upon hitting 28mph will shut itself down from production for about 5 minutes meaning that the 20mph winds if producing gusts will render the thing useless for production. as was told to me it saw about 4a typically in the columbus, ohio area when it was able to make something. too low is obvious and too high cuts it out and it needs a sweet spot to be useful. add to that blade replacements and other maintenance items associated with it and it turns out to be a money pit for its level of power production.:grr

as for the Trace inverter /charger it has failed twice -- once from lightning and the current unrepaired failure

The chart at SWW is clearly a typo since the unit does not consume any power at all

The chart in my manual rates output at 30 KWHr per month in a 12 mph average
or about a KWHr per day

this is very close to my experience with the unit powering the fridge

it is a waste of money if you do not have at least a 10 mph average site

Not to pick nits,,, but because any hardware performed for three years doesn't mean it
"paid for itself". For example,, assume for the moment that it produced 1kwh/day which is close to what the "advertised" rate would be. (pretty optimistic IMHO) you would get ~ 365 kwh/year. At $.12 grid power cost would return ~ $44 worth of power,, three years would be ~ $175 worth. Given the ~$600 cost,, it is hard to say that it paid for itself.

Now I am not saying it is not valuable to you (or to someone) but "paying for itself is somewhat relative.

Now my newest PV panel, puts out 90 watts. Using my own 50% rule of net/net off grid here is it's number. 90X50%=45 watts X 6 hours average X 365 = would be 98 kwh/year,,, $12 per year at a cost of ~$250. Roughly 1/3 the power at 1/2 the cost.

Now if you figure out which is more likely to put out as advertised, AND the life cycle cost,,, my money is with the PV panel.

Tony

In both cases I use some weather assumptions. In the wind,, we are assuming (according to SW wind) a 12mph AVEARGE,, 24/7! In my Pv case I am assuming 6 hours of sun, also pretty optimistic,,,EXCEPT, in the winter I might get as low as zero on a bad day,, 2 hours on an average day,,, and a full 6 on a great day, plus a cold weather/reflection bonus). In the summer however,, because of my latitude,, I get as many as 14 hours on a perfect day,, as low a 2 on a terrible day (very rare in summer when we don't get a couple hours of net sun) and an average of better than 8.

I think that I am like a lot of folks (including Tony) who would love a small sized wind turbine, at a reasonable price of course, for just a tiny bit of extra "power diversity". I am always a fan of having backup's, and redundancies, particularly for important stuff. I think my two biggest reasons for not getting on yet are: not enough consistent winds at my site, and two, the whole idea of having a turbine with moving parts in such a harsh environment just screams "unreliable".
Obviously in the right site the amount of available power could more than offset any inconvenience of having to work on the turbine every now and then. But there's the rub, and the issue with this (or any other) "test": there are so many variable issues that affect the potential success, or failure of a wind turbine, that a "standard test" just doesn't really do justice.
Let's see this test concludes that:
-small wind turbines are unreliable, and not cost effective at low wind speeds (while mounted at low elevations)...
did I miss anything?
I suppose this "test" might be good to point out to the uneducated that wind power is not such a simple, or certain thing, but I don't know that it really says much else.
Is "small" wind right for you or for me? That's a tough question to fully answer with this test in my oppinion. I totally agree with the suggestion earlier to have a professional inspect the site, and then tailor fit that assessment to each individual and their needs.

I wonder which were the 3 failures(or did I miss something in the report?) and I wonder how many failure there would be at a 6 m/s wind site. Where I live there are many and they are mostly far from the grid which is atrocious and more unreliable anyway.

I built a small VAWT (2’dia x 5.5’ ht) out of PVC, and mounted it on a floating dock, 50’ out into the NE Cape Fear River. I am about 18 miles from the ocean, and regularly get a strong W, NW, SW wind up the river. The VAWT works great, particularly with the deflectors I built to channel more wind to it. (As an aside: I also have an Apricus 30-tube solar water heater, pv-powered El Sid pump, that I installed from various components. We are completely off the grid for hot water 10 months out of the year.)

I am an amateur at this (wind turbine) stuff, as will soon be obvious. I am doing this as a hobby, but don’t mind sucking up 200-600 watts (or more) from my VAWT if I can get it. I am having trouble weaving through all the BS that is out there, especially where grid tied inverters for turbines are concerned. At the moment, I am using an Ametek 30VDC (I did day I was an amateur), and was foolish enough to buy an EnviroTechs inverter. The baby Ametek fried that inverter in two days. (I got a complete refund.) I eventually want to go to an Ametek 72 or 99 VDC, but even with the little 30 VDC, I do not know what to use for a grid tie inverter. Looking at SWEA, but still seems iffy. SMA’s Windy Boy 700u seems to be a quality inverter at the range I could use. Any suggestions?

You will also need consider potential noise of using a rooftop wind turbine. Many people agree that vertical axis turbines are quieter than other models. As noted above, placement is key to gain the most favorable winds and efficiency. If you have a pitched roof, consider placing the wind turbine in a higher location. For flat roofs, towards the edge.

Each day, hundreds of new rooftop wind turbines are installed across the country. Wind turbine manufacturers are busier than ever, and people looking for green jobs are finding them in the wind sector of the renewable energy industry, in part because of the rapid growth. By tapping into wind power, property owners are watching their electrical meters roll backwards, allowing them to save money while doing their part to save the planet.

Amazingly, consumers that installed residential rooftop wind turbines, cut their utility bills by 50-90%. Considering the fact that prices range from $5-10,000 for most systems (before tax credits and rebates), it can pay for itself in a few years.

...

At a mere 36 inches tall, the plug-in wind appliance can generate about 40 kilowatt hours each month, that’s enough to light a home using high-efficiency bulbs, said [Inventor Chad] Maglaque. And although micro-wind is nothing new, at $400 a pop, the Jellyfish’s price and simplicity make it a fresh face in the market. [Via Worldchanging]

One of the problems with these type of "Green Articles" is that they lead to conclusions like this (link from above article, to another on wind):

Proposed: A Wind Electric Co. generator system behind my house (N side), to generate 700-1000 W per month. System will store generated electricity in batteries to be used directly by my residence. As needed, I will continue to draw power from the grid.
I am in need of financing or a grant/tax credit. System has capacity to begin generating at just 3 mph
Estimated total cost of install approx. $10,000
Note: To date, no other residence within city limits of Eugene, OR has such a system. City coordidator for building permits says I am breaking new ground. I have told city and manufacturer I am eager to be a beta test site; I will invite news media and city, county, state, others to come here to collect data and do research studies.
I sincerely want this type of project to become a reality for myself and others.

Our Small Wind Residential Generators are rated to produce 2K to 4K watts in a 24 hour period. Our Windmill power has a cut-in wind speed of 3 mph, making it possible to create power with little wind virtually all day and night.

9' turbine with 1,000 watts peak at 16 mph... (I guess--there are no graphs that I could find).

Not quite sure that I would drop $5-$10,000 with a company that (apparently) does not know the difference between 4 kWatt and 4 kWatt*Hours...